The ArmaLite Rifle AR-10 is a 7.62×51mm NATO caliber battle rifle developed by Eugene Stoner and manufactured by ArmaLite during the 1950s. The rifle used an innovative straight-line stock design, rugged elevated sights and forged alloy parts resulting in a small arm significantly easier to control in automatic fire that is lighter than other infantry rifles of the day.
But the more famous of the AR Family is the AR 15, which became the M16 family of rifles we all know and recognized today.
Various countries used them and many variations made in various countries and some using a short stroke piston instead of the Direct Gas Impingement, the AR-15 Family of Rifles becomes the rifle famous with Military Units, Police Units and now active shooters due to the accessibility in the Gun market of today.
But History rarely tells you everything, while the US Military was indecisive with the AR Family Rifles a lot of countries adopted the AR-10s and early AR-15s, as the AR-10 was produced overseas to foreign buyers looking to equip their militaries with modern hard hitting combat rifles, for example: Guatemala, Burma, Italy, Cuba, Sudan and Portugal purchased AR-10 rifles for limited issue to their military forces.
But for the AR-15, their first official used was not the US Military but in an Archipelago Country in South East Asia, fighting Insurgencies and picking fights with former European Colonies, Indonesia, since the nation was in need of a light rifle to substitute the BM59 Rifles and other WW2 era weapons and equipment.
The Nation in need of more modern weapons thus look around the world for weapons and equipment, like the Early G3s which are adopted by Air Force Paratroopers and the AR-15 Rifles adopted by the Police Tactical Unit, BRIMOB (Brigade Mobil / Mobile Brigade) more specifically Ranger Regiments now known as the Pioneer Troops or Pelopor.
Beloved for it’s light weight and hard hitting rounds, the AR-15 becomes the most popular rifle in the Police Force and the Presidential Bodyguard Force (Tjakrabirawa Troops), but as President Sukarno leans more into Communism, the sales of the rifles were hit by US Embargo thus preventing the Force from getting more, but in this background, the US Military has started to gain interest.